Otto von Guericke (November 20, 1602 – May 11, 1686) was a German scientist, inventor, and politician. His major scientific achievements were the establishment of the physics of vacuums, the discovery of an experimental method for clearly demonstrating electrostatic repulsion, and his advocacy of the reality of "action at a distance" and of "absolute space".
In 1654 von Guericke invented a vacuum pump consisting of a piston and an air gun cylinder with two-way flaps designed to pull air out of whatever vessel it was connected to, and used it to investigate the properties of the vacuum in many experiments. This pump is described in Chapters II and III of Book III of the Experimenta Nova and in the Mechanica Hydraulico-pneumatica (p. 445-6). Guericke demonstrated the force of air pressure with dramatic experiments.
In 1657, he machined two 20-inch diameter hemispheres and pumped all the air out of them, locking them together with a vacuum seal. The air pressure outside held the halves together so tightly that sixteen horses, eight harnessed to each side of the globe, could not pull the halves apart. It would have required more than 4,000 pounds of force to separate them.